simulinterrupt.ino

#define XPIN 2
#define YPIN 3
#define X 0
#define Y 1

volatile short timeHigh[2]    = {0, 0};
volatile short timeLow[2]     = {0, 0};
volatile long  lastFalling[2] = {0, 0};
volatile long  lastRising[2]  = {0, 0};

void setup() {
  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(XPIN), Xdutycycleupdate, CHANGE);
  attachInterrupt(digitalPinToInterrupt(YPIN), Ydutycycleupdate, CHANGE);
}

void loop() {
  if ((millis() / 10000) % 2) {
    Serial.println(checkDutyCycle(X));
  } else {
    Serial.println(checkDutyCycle(Y));
  }
  delay(10);
}

void Xdutycycleupdate() {
  digitalRead(XPIN) ? risingUpdate(X) : fallingUpdate(X);
}

void Ydutycycleupdate() {
  digitalRead(YPIN) ? risingUpdate(Y) : fallingUpdate(Y);
}

// called after the signal has been high, on a falling signal.
void fallingUpdate(byte axis) {
  lastFalling[axis] = micros();
  timeHigh[axis] = lastFalling[axis] - lastRising[axis];
}

void risingUpdate(byte axis) {
  lastRising[axis] = micros();
  timeLow[axis] = lastRising[axis] - lastFalling[axis];
}

byte checkDutyCycle(byte axis) {
  return map(timeHigh[axis], 0, timeLow[axis] + timeHigh[axis], 0, 255);
}